Palladium Catalyzed Domino Sonogashira Coupling of 2-Chloro-3-(Chloromethyl)Quinolines with Terminal Acetylenes Followed by Dimerization

A domino Sonogashira coupling of 2-chloro-3-(chloromethyl)quinolines and terminal acetylenes and then dimerization is described. This palladium-catalyzed reaction gave novel dimer quinolinium salts in good to high yield. Based on empirical evidence, a plausible mechanism was provided. The produced quinolinium salt are amenable to further synthetic elaborations such as reactions with phenoxide and thiophenoxide to yield the corresponding ether and thioether.